1. Field of the Invention
The present invention relates to a picture image processing system of the picture image storage type which temporarily stores and accumulates picture image data temporarily read into the system.
2. Discussion of the Related Art
A picture image storage type electrophotographic copying machine is comprised of a reading device, a storage device, and a picture image output device, and offers many such functions as electronic RDH (Recirculating Document Handler), reverse sequence output, and sample copying. Picture images (original documents) need be read only once by a reading device, such as a digital raster scanner, and then stored in picture image files with associated job parameters. The job parameters are operating instructions for the picture image processing system and include instructions on such items as the paper size and paper orientation, the number of pages, the number of chromatic grades or shades, colors, binding margin, and photographic modes. (The operating instructions will be sometimes referred to as "the parameters" in this specification.) The storage device may be a hard disk from which picture images may be read and printed in a regular sequence.
This type of system enables the operator to obtain a sample copy for confirmation of the contents and then to produce large quantities of copies, with corrections made as necessary, and also to have the equipment read and store parts of an original document in advance, to expedite subsequent processing operations, even if all of the sheets of the original document are not ready.
Highly dense images generate picture image data in an enormous amount, e.g., up to four megabytes for a single sheet of binary picture images with 600 by 600 dpi on a standard A-4 size sheet. Even if the picture image data is compressed, the amount of picture image data may be as large as several hundred kilobytes. Conventional picture image processing systems, such as the electrophotographic copying machine mentioned above, has had the shortcoming that the system will not have sufficient storage capacity in the hard disk for a sufficient number of documents.
File security and prevention of unauthorized access of files are serious problems with a conventional system such as the one just described. There is a significant risk that a third party may print or modify the stored picture image datafiles without permission.